Safety switch mechanism

ABSTRACT

A safety switch mechanism for use in connection with a recoil starter using a rope or cable. Such a starter is used on the usual internal combustion engine mounted on a vehicle such as a tractor which carries with it a powered tool such as a grass cutting unit. The mechanism is particularly adapted for safety systems wherein the engine is short-circuited so that the engine can not be started by pulling the rope or cable unless both the clutch of the tractor and the clutch of the powered tool are disengaged. This safety switch mechanism has a unique construction enabling it to be locked in open position so that the switch mechanism is not inadvertently opened by vibration or other means after the engine is started and the tractor and powered tool are being used. This is an abstract only of the specific illustration of the invention given by way of example, and is not to be used in the interpretation of the claims nor as a limitation on the scope of the invention.

United States Patent Plamper et a1.

Jan. 1, 1974 SAFETY SWITCH MECHANISM [75] Inventors: Gerhard R. Plamper,Parma;

Juergen Kaesgen, Brunswick, both of Ohio [73] Assignee: MTD ProductsInc., Cleveland,

Ohio

[22] Filed: Nov. 6, 1972 [21] Appl. No.: 304,072

[52] US. Cl. 200/161, 192/098, 180/82 R, 307/10 R [51] Int. Cl. H0lh17/08 [58] Field of Search 192/.084, .98; 180/82 R; 56/D1G. 15; 200/161,61.59, 51.1; 307/10 R [56] References Cited UNITED STATES PATENTS1,017,948 2/1912 Boyston 200/51.1 2,117,066 5/1938 Liverancc, Jr.200/153 M 2,490,675 12/1949 Clare ZOO/161 3,626,676 12/1971 Miley ct a1192/.098

Primary ExaminerDavid Smith, Jr. Attorney-George V. Woodling et al.

[57] ABSTRACT A safety switch mechanism for use in connection with arecoil starter using a rope or cable. Such a starter is used on theusual internal combustion engine mounted on a vehicle such as a tractorwhich carries with it a powered tool such as a grass cutting unit. Themechanism is particularly adapted for safety systems wherein the engineis short-circuited so that the engine can not be started by pulling therope or cable unless both the clutch of the tractor and the clutch ofthe powered tool are disengaged. This safety switch mechanism has aunique construction enabling it to be locked in open position so thatthe switch mechanism is not inadvertently opened by vibration or othermeans after the engine is started and the tractor and powered tool arebeing used. This is an abstract only of the specific i1- lustration ofthe invention given by way of example, and is not to be used in theinterpretation of the claims nor as a limitation on the scope of theinventron.

was

SAFETY SWITCH MECHANISM This invention is related to, and constitutesimprovement upon, the system disclosed in U.S. Pat. No. 3,626,676.Reference is made to that patent for a discussion of the background ofthe invention and for a discussion of the general purposes of such asafety switch actuated short-circuiting system.

In tractors or the like embodying the safety system disclosed in saidU.S. Pat. No. 3,626,676, the safety switch tends to inadvertently openand close by vibration during use of the tractor and other means so thatcontinued uninterrupted operation of the engine is not assured. Oursafety switch mechanism provides a positive lock so that after theengine is started, with both clutches disengaged, then the tractor andthe powered tool may be operated in the usual manner without danger ofthe engine being short-circuited and itsceasing to operate. The objectsand advantages of our mechanism will become apparent upon considerationof the accompanying drawings and description.

An object of our invention is to provide improved operation of a tractorhaving a safe-start system which assures that the engine can not bestarted up by the recoil mechanism unless and until both the clutch ofthe tractor and the clutch of the powered tool are disengaged.

Another object is the provision for assuring improved and more efficientoperation and use of the safety system.

Other objects and a fuller understanding of this invention may be had bereferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a side view of a mowing riding tractor to which the presentinvention is adapted as shown by way of example;

FIG. 2 is a diagrammatical view, including a circuit, illustrating thelayout and operation of our improved system;

FIG. 3 is an enlarged view, partly in section, of our improved safetyswitch mechanism and showing the switch in open position and locked insuch open position;

FIG. 4 is a view similar to that of FIG. 3 but showing the safety switchin closed position and not locked in open position; and

FIG. 5 is a partial view of the safety switch mechanism looking in thedirection of the arrows 5-5 of FIG. 4.

The tractor illustrating a use of our improved mechanism is indicated bythe reference character 11 in FIG. 1. A powered cutting unit 12 issuspended below the tractor 11 in the usual way and the cutting unit hasits cutting blades rotated in the usual manner by the power of thetractor through suitable power transmitting means. The tractor 11 andthe cutting unit 12 each have a clutch. The clutch of the tractor 11controls the transmission between the tractor engine 13 and the drivingwheels of the tractor. The clutch of the cutting unit controls the powertransmission between the cutting unit 12 and the engine 13. As theseclutches are usual and their structure and operation is well known, theyhave not been illustrated in FIG. 1.

It is of course dangerous to start a tractor such as a powered mowingtractor, by pulling out the rope or cable of the recoil mechanism 14unless both clutches are disengaged, otherwise there is a danger thatthe tractor may start moving as soon as the engine started and also thatthe cutting unit might start to operate as soon as the engine started.Therefore it is desired that both the tractor clutch and the cuttingunit clutch be disengaged before the engine can be started by pullingout the rope or cable 48 of the recoil starting mechanism 14. The engine13 includes a visual ignition system which may be tapped such as at 15for shortcircuiting the ignition system to make the engine inoperable.As is well known, the engine may be stopped and prevented from operatingby short-circuiting the ignition system at 15 by providing a groundconnection between such ignition system and the ground. In such a systemthe frame of the tractor is usually utilized as ground.

In our safe start system we utilize a wire 16 in connection with theelectrical ignition system for the engine. As the ignition system isusual and well known, we have not shown the entire electrical ignitionsystem but only wire 16 thereof which is utilized for our safety system.The wire 16 leads to the ignition switch 17 operated by a key in theusual manner.

Our system utilizes two normally closed switches 18 and 19. Switch 18 ismoved or actuated by an actuating element 20 which through a linkage 22is operated by the clutch of the tractor 11, for example. When thetractor clutch is disengaged, then the switch 18 is open by means of theelement 20 and linkage 22.

The other normally closed switch 19 is moved or actuated by an actuatingelement 21 which in turn is actuated by a linkage 23 connected to theclutch of the cutting unit 12. Upon the disengagement of the cuttingunit clutch the switch 19 is opened by the element 21 and linkage 23.

A wire 24 connects one pole or contact of each of the switches 18 and19. Another wire 25 connects the other poles or contacts of the switches18 and 19. The wire 25 is tapped at 28A to wire 26 and through wire 26is tapped at 27 to wire 16. Wire 16 at its one end is connected toignition system at 15. The other end of wire 16, as explained, isconnected to the ignition switch 17. A wire 29 is tapped at 28 to wire24. FIG. 2 shows the arrangement of the wires and connections described.It is thus seen that switches 18 and 19 as connected in parallel is acircuit made up of wires 24 and 25. The said circuit being connected towire 16 to the ignition system at 15, and also being connected as shownto wire 29.

The safety switch mechanism is shown diagrammatically in FIG. 2, but itsstructure is shown in full and enlarged in FIGS. 3, 4 and 5. As seen inFIGS. 3, 4 and 5, there is a metal bracket 31 mounted upon the frame 49of the tractor 11. Thus the metal bracket 31 is connected to ground bymeans of being mounted to the metal frame 49. This bracket 31 extendsvertically upwardly from the frame at the rearwardmost end of thetractor or on side thereof for convenience and safety. An operatordesiring to actuate the recoil mechanism by pulling out the startingrope or cable stands rearwardly or sidewardly of the tractor.

Mounted to the upper portion of the bracket 31 is a plate member 32which has side portions which are secured to the bracket 31 by means ofbolt and nut as semblies 33. As seen, the plate member 32 is U-shapedand there is provided an open space between the main portion of theplate member 32 and the bracket 31. The main portion of the plate member32 and the upright portion of the bracket 31 are parallel and spacedapart.

There is provided in the vertical portion of the bracket 31 near itsupper end a rectangular shaped opening 34. The major axis of thisrectangular opening 34 is generally horizontal as better seen in FIG. 5.Aligned with this opening 34 is a smaller round hole 35 in the platemember 32. The aligned holes 34 and 35 accomodate a rope or cable 48which is pulled out from the recoil starting mechanism in the usualmanner for the starting of the engine. To provide a guide for the rope abushing 38 is mounted in the opening 35 as illustrated. It may be ofnylon or other suitable material against which the rope or cable maybear in its longitudinal movement. Mounted to the plate member 32 is aleaf spring 39 in such a manner as to be biased or resiliently urgedtoward the position shown in FIG. 4. The lower end of the leaf spring 39extends through a slot 36 in the lower end portion of the plate member32 and abuts against the bent-over portion 37. In this manner the leafspring is anchored to the lower end of the plate member 32 in a mannerto resiliently urge the upper end of the leaf spring 39 to the left inFIGS. 3 and 4, that is toward its position shown in FIG. 4. An opening40 is provided in the leaf spring 39 intermediate of its ends foraccomodating the bushing 38. The leaf spring may freely swing in itsmovement without interference from the bushing 38.

Mounted upon the upper free end of the leaf spring 39 is a movableswitch element 42. The switch element 42 is electrically insulated fromthe metal spring 39 by fibre washers 41. This switch element 42 is abolt secured in a fitting 43 which is suitably electrically insulatedbut provides that the switch element 42 is electrically connected to thewire 29 through the fitting 43. The upper end of the bracket 31 facingthe switch element 42 has a contact surface indicated by the referencecharacter 31A. Thus when the switch element 42 is swung to the left inFIGS. 3 and 4 under the bias of leaf spring 39, the switch element 42electrically engages the contact surface 31A as shown in FIG. 4.

Firmly secured to the outer or free end of the starting rope or cable 48is a starting or actuating member 44. This member 44 has a handleportion 45, a shank portion 46, and a locking portion 47. Preferablyportions 45, 46 and 47 are integral and are molded of a suitable plasticmaterial. There is a space between the portion 45 and the portion 46 foraccommodating the fingers of an operator seizing the handle portion 45and for pulling the rope or cable 48 outwardly, that is toward the leftin FIGS. 3 and 4.

The locking portion 47 is rectangular in cross-section and complementsthe rectangular opening 34 in the bracket 31, although slightly smallerin dimensions than the opening 34. The shape and dimensions of thelocking portion 47 relative to the shape and dimensions of the opening34 in bracket 31 are such that when the actuating member 44 is orientedin one position, such as when the major axis of the locking portion 47is parallel to the major axis of the rectangular opening 34, then thelocking portion 47 may freely move in and out through the opening 34.However, the shape and dimensions of the locking portion 47 and opening34 are such that when the actuating member 44 is oriented into anotherposition, then the locking portion 47 can not move through the opening34. For example, upon the major axis of the rectangularly shaped lockingportion 47 being disposed in a vertical line, such as shown in FIG. 3,then the locking portion 47 can not move through the opening 34. If ithas already been inserted through the opening 34 by being properlyturned and then is thereafter turned so as to assume the positionillustrated in FIG. 3, then the locking portion is firmly locked withinthe open space between the bracket 31 and plate member 32. When in thislocked position the spring 39 is opposed against its resilient bias toforce and to hold the switch element 42 out of electrical engagementwith the contact surface 31A and thus to break or open the electricalconnection between the wire 29 and ground through the frame 49.

When it is desired to pull on the rope or cable 48, the handle portion45 is seized and turned to a angle from its original position, that isso that the major part of the locking portion 47 is parallel with themajor axis of the opening 34, then the locking portion 47 may be pulledout through the opening 34, such as to its position shown in FIG. 4.Thus when the rope or cable 48 is being pulled by outward extension ofthe actuating member 44, spring 39 moves the switch element 42 intoelectrical engagement with the contact surface 31A of the bracket 31 andthis electrically interconnects the wire 29 and ground through thebracket 31 and frame 49.

It is therefore seen that when the recoil starting mechanism is beingoperated by pulling out on the rope or cable 48, the safety switchmechanism is closed and the wire 29 is grounded. This provides anelectrical connection to the engines ignition system at 15 through thecircuit made up of wires 24 and 25 if either of the switches 18 or 19 isclosed by reason of its respective clutch being engaged. This willprevent operation of the engine if either clutch is engaged. It is to benoted that if the safety switch mechanism is open by being locked inopen position by the structure illustrated, then the engine may beoperated. The locking of the safety switch mechanism into open positionafter the engine has been started permits the tractor to be operated andthe cutting unit to be operated through the usual engagement of theirrespective clutches.

To aid in preventing the actuating member 44 and its locking portion 47from being accidently rotated through vibration or otherwiseinadvertently after it has been inserted through opening 34 and rotated90 to the position illustrated in FIG. 3, there is provided on the leafspring 39 a boss or off-set portion 39A protruding toward bracket 31 asshown in FIGS. 3 and 4. The locking portion 47 has a groove orlongitudinal recess 47A formed therein which may accomodate the boss39A. The sides of the boss 39A are sloping so that the boss 39A mayslidably or cammingly enter into the groove 47A.

It will be understood that the bias of leaf spring 39 will urge the boss39A to remain in the groove 47A when in the position of FIG. 3. However,by forcibly rotating locking portion 47 the boss 39A may escape thegroove 47A. The arrangement provides means that may be manually overcomefor holding the parts in the position of FIG. 3.

It will be seen that a safer and more efficient safety start system ishere provided by the safety switch mechanism herein shown and described.

The present disclosure includes that contained in the appended claims,as well as that of the foregoing description.

Although this invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

1. In an electrical grounding system for a device having an electricallyconductive frame, an internal combustion engine mounted on said frameand grounded thereto, an elongated starting member such as a rope orcable to be manually extended for starting the engine, a first clutchfor controlling one function of the device, a first switch controlled bythe positions of said first clutch in clutched and unclutched condition,a second-clutch for controlling a second function of the device, asecond switch controlled by the positions of said second clutch inclutched and unclutched condition, an electrical ignition system forsaid engine, and an electrical circuit for connecting said first andsecond switches in parallel with ground and with the electrical ignitionsystem of the engine for grounding the ignition system and preventingoperation of the engine upon closing of said electrical circuit by theclosing of either of said first and second switches by the positioningof either said first and second clutches, respectively, in clutchedcondition, the improvement of a safety switch mechanism mounted on saiddevice comprising the combination of a mounting bracket carried by saiddevice and grounded to said frame, said bracket having two spacedportions defining an open space therebetween, one of said bracketportions having an electrical contact surafce, a movable switch elementcarried by the bracket movable into and out of electrical engagementwith said contact surface, said movable switch element beingelectrically connected to said electrical circuit for connecting anddisconnecting said electrical circuit with ground, biasing means carriedby said bracket and insulated from said movable switch element forbiasing said movable switch element into electrical engagement with saidcontact surface, said two bracket portions having aligned openingsthrough which said elongated starting member extends, an actuatingmember secured to the free end of said elongated starting member, saidactuating member having a handle portion adapted to be manually seizedfor extending the elongated starting member, having a locking portion,and a shank portion extending between said handle portion and lockingportion, the said opening in one of said bracket portions being shapedand dimensioned relative to the cross-sectional shape and size oflocking portion and shank portion to permit the said shank portion topass therethrough but to bar said locking portion to pass therethroughexcept as the locking portion is oriented relative to the said openingin the one said bracket portion, said locking portion upon beingoriented to be passable through the said one opening into the said openspace between the said bracket portions and to be lockable therein bybeing moved out of orientation, and to be removable therefrom by beingoriented to pass through the said one opening, said locking portion insaid open space engaging and opposing said biasing means to hold saidmovable switch element out of electrical engagement with said contactsurface, the said safety switch mechanism upon the electrical engagementof said movable switch element and the said contact surface connectingthe said electrical circuit with ground and upon the electricaldisengagement of said movable switch element by said locking portiondisconnecting the said electrical circuit with ground.

2. A safety switch mechanism as claimed in claim 1 and in which saidbiasing means is a leaf spring anchored to one of said bracket portionsand carries said movable switch element on its free end resilientlyurges the movable switch element against said contact surface.

3. A safety switch mechanism as claimed in claim 1 and in which saidlocking portion of the actuating member is non-circular in cross-sectionand is dimensioned in cross-section greater than said shank portion, andthe opening in the bracket portion through which the locking portion ispassed is non-circular and dimensioned in cross-section so as to permitthe locking portion to be passed therethrough into said open space uponthe positioning of the actuating member to place the said lockingportion in correspondence with said opening, and so as to lock thelocking portion in said open space upon the positioning of the actuatingmember to place the said locking portion out of correspondence with saidopening.

4. A safety switch mechanism as claimed in claim 1 and in which thehandle portion, shank portion and locking portion of the actuatingmember are inegrally molded plastic material, and the handle portion andlocking portion are rectangular in cross-section and similarly oriented,and in which the shank portion has an axial length to accomodate betweenthe handle portion and locking portion the fingers of the operatorseizing the handle portion.

1. In an electrical grounding system for a device having an electricallyconductive frame, an internal combustion engine mounted on said frameand grounded thereto, an elongated starting member such as a rope orcable to be manually extended for starting the engine, a first clutchfor controlling one function of the device, a first switch controlled bythe positions of said first clutch in clutched and unclutched condition,a second clutch for controlling a second function of the device, asecond switch controlled by the positions of said second clutch inclutched and unclutched condition, an electrical ignition system forsaid engine, and an electrical circuit for connecting said first andsecond switches in parallel with ground and with the electrical ignitionsystem of the engine for grounding the ignition system and preventingoperation of the engine upon closing of said electrical circuit by theclosing of either of said first and second switches by the positioningof either said first and second clutches, respectively, in clutchedcondition, the improvement of a safety switch mechanism mounted on saiddevice comprising the combination of a mounting bracket carried by saiddevice and grounded to said frame, said bracket having two spacedportions defining an open space therebetween, one of said bracketportions having an electrical contact surface, a movable switch elementcarried by the bracket movable into and out of electrical engagementwith said contact surface, said movable switch element beingelectrically connected to said electrical circuit for connecting anddisconnecting said electrical circuit with ground, biasing means carriedby said bracket and insulated from said movable switch element forbiasing said movable switch element into electrical engagement with saidcontact surface, said two bracket portions having aligned openingsthrough which said elongated starting member extends, an actuatingmember secured to the free end of said elongated starting member, saidactuating member having a handle portion adapted to be manually seizedfor extending the elongated starting member, having a locking portion,and a shank portion extending between said handle portion and lockingportion, the said opening in one of said bracket portions being shapedand dimensioned relative to the cross-sectional shape and size oflocking portion and shank portion to permit the said shank portion topass therethrough but to bar said locking portion to pass therethroughexcept as the locking portion is oriented relative to the said openingin the one said bracket portion, said locking portion upon beingoriented to be passable through the said one opening into the said openspace between the said bracket portions and to be lockable therein bybeing moved out of orientation, and to be removable therefrom by beingoriented to pass through the said one opening, said locking portion insaid open space engaging and opposing said biasing means to hold saidmovable switch element out of electrical engagement with said contactsurface, the said safety switch mechanism upon the electrical engagementof said movable switch element and the said contact surface connectingthe said electrical circuit with ground and upon the electricaldisengagement of said movable switch element by said locking portiondisconnecting the said electrical circuit with ground.
 2. A safetyswitch mechanism as claimed in claim 1 and in which said biasing meansis a leaf spring anchored to one of said bracket portions and carriessaid movable switch element on its free end resiliently urges themovable switch element against said contact surface.
 3. A safety switchmechanism as claimed in claim 1 and in which said locking portion of theactuating member is non-circular in cross-section and is dimensioned incross-section greater than said shank portion, and the opening in thebracket portion through which the locking portion is passed isnon-circular and dimensioned in cross-section so as to permit thelocking portion to be passed therethrough into said open space upon thepositioning of the actuating member to place the said locking portion incorrespondence with said opening, and so as to lock the locking portionin said open space upon the positioning of the actuating member to placethe saId locking portion out of correspondence with said opening.
 4. Asafety switch mechanism as claimed in claim 1 and in which the handleportion, shank portion and locking portion of the actuating member areintegrally molded plastic material, and the handle portion and lockingportion are rectangular in cross-section and similarly oriented, and inwhich the shank portion has an axial length to accomodate between thehandle portion and locking portion the fingers of the operator seizingthe handle portion.